The main purpose of this project is to determine the therapeutic efficacy of lecithin in tardive dyskinesia. In a double-blind cross-over experiment, 50 psychiatric patients with moderate or severe tardive dyskinesia will receive lecithin 50 g/day for 1 month, and placebo for 1 month. Effect on rardive dyskinesia will be evaluated by the AIMS rating of videotaped interviews as well as by polygraphic recording and computer analyses of orofacial movements. Respiratory movements will also be recorded and analyzed. Blood levels of lecithin, choline, and acetylcholine will be determined.